The Check-Digit Calculator uses a nine-digit base number to calculate a unique 11-digit Texas Identification Number (TIN).

An 11-digit TIN has three components: the one-digit prefix number, nine-digit base number and one-digit self-check number. The nine-digit base number is usually a Federal Employer Identification Number (EIN), Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN). TINs can also be randomly assigned 11-digit numbers that begin with 7.

The Check-Digit Calculator calculates a TIN number based on the EIN or SSN/ITIN for reference purposes only. Before a payee can receive payment from the state of Texas, the payee must be set up in the Texas Identification Number System (TINS).